Objective:

To analyze the associations of inflammatory indices with laboratory-defined organ injury/involvement and hospitalization length in pediatric respiratory tract infections (RTIs).

Approach:

• Logistic Regression Analysis: Examined associations between inflammatory index levels and laboratory-defined cardiac injury, liver injury, and kidney involvement.
• ROC Curve Analysis: Evaluated the discriminative ability of inflammatory indices for laboratory-defined organ injury/involvement.
• Linear Regression Analysis: Assessed associations between inflammatory index levels and hospitalization length.

Key Findings:

• Lower levels of neutrophils, CRP, SII, NLR, NPR, and CLR were associated with the presence of laboratory-defined cardiac injury.
• Higher lymphocyte levels and lower levels of neutrophils, platelets, CRP, SII, NLR, PLR, NPR, and CLR were associated with the presence of laboratory-defined liver injury.
• Higher levels of WBCs, neutrophils, CRP, SII, NLR, PLR, and CLR, along with lower lymphocyte levels, were associated with the presence of laboratory-defined kidney involvement.
• NLR, SII, and CLR had high discriminative ability for laboratory-defined cardiac injury; SII, NLR, and PLR for laboratory-defined liver injury; NLR, CLR, and NPR for laboratory-defined kidney involvement.
• Higher levels of WBCs, lymphocytes, CRP, NPR, and CLR, along with lower levels of platelets and Hb, were associated with longer hospitalization.

Interpretation:

Inflammatory indices, particularly composite indices, were associated with laboratory-defined organ injury/involvement and longer hospitalization in children with RTIs.

Limitations:

• Study conducted in a single hospital, which may limit generalizability.
• Potential confounding factors not accounted for in the analysis.

Conclusion:

Inflammatory indices derived from routine blood tests may serve as non-invasive exploratory markers for organ injury and hospitalization length in pediatric RTIs.